Eccentrically loaded slender columns strengthened by high-strength fiber reinforced concrete jackets

الملخص EN

The behavior of eccentrically loaded cracked slender High-Strength Concrete (HSC) columns strengthened by HSC jackets contain steel fibers and have cube compressive strength equal to 89.3 MPa has been studied experimentally.

The results of these tests have been used to examine the applicability of the design requirements of slender columns of the Eurocode 2 (EC-2), the Egyptian code (ECCS-2001) and ACI 318-99 building code, when applied to the strengthened columns.

The testing program included 11 columns with slenderness ratios before strengthening ranged between 17.3 and 69.3.

The main variables considered in this study were the slenderness ratio of the strengthened columns, the type of the steel fibers, the end eccentricity of the applied axial load and the transverse reinforcement ratio of the HSC jackets.

The results showed that, eccentrically loaded slender and short cracked columns strengthened by HSC jackets contain 1 % steel fibers (by volume) can be treated as new integral columns.

Using a steel fibers into the HSC mix of the jackets reduces to a great extent the early cover spalling of the tested columns and increases the ultimate loads comparing with the same columns strengthened with HSC jackets without steel fibers.

The three different methods for design of slender columns required by the ECCS-2001, EC-2 and ACI 318-99 building code can be safely used for design of slender columns strengthened by HSC jackets contain steel fibers.